The proposed study will examine the usefulness and reliability of examining the cytoskeletal structure of cells, alone and in tissue, by immunohistochemical techniques in normal and neoplastic states. Antisera against actin, alpha-actinin, tropomyosin, tubulin and smooth myosin derived from several sources will be prepared in rabbits. Antibodies will be purified by affinity chromatography, assayed for content, and for specificity using tissue culture systems (normal and transformed cells), routine immunofluorescence and immunoelectronmicroscopy employing a peroxidase label. The reproducibility of procedures and the variation between antibody producers will be examined. The value of this system in differentiating between normal and transformed (or malignant) cells will be considered in both experimental models as well as in human disease. This preliminary study will be limited to the examination of tumors of skin, colon, breast, lymphoid tissue and respiratory tract (cytology).